Research suggests that rising spending, inadequate quality, and a fragmented delivery system characterize the current U.S. health care system. There is growing interest in the patient-centered medical home (PCMH) as one approach to care delivery and payment aimed at improving quality and reducing costs by better coordinating care and meeting the unique needs of patients through enhanced primary care. This study will evaluate the New Hampshire Citizens Health Initiative Multi-Stakeholder Medical Home Pilot, a multi-payer demonstration of the PCMH model in nine health care organizations in New Hampshire, to better understand if and how the PCMH model can improve quality and reduce costs. This study is an empirical evaluation of the process of practice redesign, and the impact of four key elements on utilization, costs, and quality-the PCMH itself, the level of medical homeness, site-level relational coordination, and organizational characteristics. The process of practice redesign will be assessed through case studies at the nine pilot sites, including interviews with members of the organization and document reviews. Surveys of relational coordination and Medical Home Index self-assessments will be administered to the pilot and comparison sites in New Hampshire. A quasi- experimental, pre-post design will be used to assess the impact of the PCMH on utilization, costs, and quality using the New Hampshire Comprehensive Health Care Information System (NH CHIS). In addition, medical homeness, relational coordination, and organizational characteristics will be included in the model to assess the impact of these constructs on utilization, cost, and quality outcomes of PCMH pilot sites, compared to non- PCMH sites. The dependent variables of interest will include utilization measures such as ambulatory care sensitive hospitalizations, emergency department visits, and readmissions. Cost measures will include total costs per member per month, as well as the costs associated with specific utilization measures. Quality measures will encompass both process and outcome measures related to preventive and chronic care. Difference-in-differences and random effects models will be used to estimate the effects of the PCMH on these dependent variables. In the context of growing interest in the PCMH model, this study will offer insight into how the PCMH can be adapted in different contexts, the lessons learned for implementing practice redesign, and the potential for certain components of the model to differentially impact health care utilization, cost, and quality outcomes. PUBLIC HEALTH RELEVANCE: Narrative In the context of growing interest in the PCMH model, this study will offer insight into how the PCMH can be adapted in different contexts, the lessons learned for implementing practice redesign, and the potential for certain components of the model to differentially impact health care utilization, cost, and quality outcomes. This has significant implications for policymakers, practitioners, and payers as they continue to grapple with effective approaches to reducing costs and improving quality across the U.S. health care system.